Commit 3cbdc8d8 authored by Akhil P Oommen's avatar Akhil P Oommen Committed by Rob Clark

drm/msm: Fix a null pointer access in msm_gem_shrinker_count()

Adding an msm_gem_object object to the inactive_list before completing
its initialization is a bad idea because shrinker may pick it up from the
inactive_list. Fix this by making sure that the initialization is complete
before moving the msm_obj object to the inactive list.

This patch fixes the below error:
[10027.553044] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000068
[10027.573305] Mem abort info:
[10027.590160]   ESR = 0x96000006
[10027.597905]   EC = 0x25: DABT (current EL), IL = 32 bits
[10027.614430]   SET = 0, FnV = 0
[10027.624427]   EA = 0, S1PTW = 0
[10027.632722] Data abort info:
[10027.638039]   ISV = 0, ISS = 0x00000006
[10027.647459]   CM = 0, WnR = 0
[10027.654345] user pgtable: 4k pages, 39-bit VAs, pgdp=00000001e3a6a000
[10027.672681] [0000000000000068] pgd=0000000198c31003, pud=0000000198c31003, pmd=0000000000000000
[10027.693900] Internal error: Oops: 96000006 [#1] PREEMPT SMP
[10027.738261] CPU: 3 PID: 214 Comm: kswapd0 Tainted: G S                5.4.40 #1
[10027.745766] Hardware name: Qualcomm Technologies, Inc. SC7180 IDP (DT)
[10027.752472] pstate: 80c00009 (Nzcv daif +PAN +UAO)
[10027.757409] pc : mutex_is_locked+0x14/0x2c
[10027.761626] lr : msm_gem_shrinker_count+0x70/0xec
[10027.766454] sp : ffffffc011323ad0
[10027.769867] x29: ffffffc011323ad0 x28: ffffffe677e4b878
[10027.775324] x27: 0000000000000cc0 x26: 0000000000000000
[10027.780783] x25: ffffff817114a708 x24: 0000000000000008
[10027.786242] x23: ffffff8023ab7170 x22: 0000000000000001
[10027.791701] x21: ffffff817114a080 x20: 0000000000000119
[10027.797160] x19: 0000000000000068 x18: 00000000000003bc
[10027.802621] x17: 0000000004a34210 x16: 00000000000000c0
[10027.808083] x15: 0000000000000000 x14: 0000000000000000
[10027.813542] x13: ffffffe677e0a3c0 x12: 0000000000000000
[10027.819000] x11: 0000000000000000 x10: ffffff8174b94340
[10027.824461] x9 : 0000000000000000 x8 : 0000000000000000
[10027.829919] x7 : 00000000000001fc x6 : ffffffc011323c88
[10027.835373] x5 : 0000000000000001 x4 : ffffffc011323d80
[10027.840832] x3 : ffffffff0477b348 x2 : 0000000000000000
[10027.846290] x1 : ffffffc011323b68 x0 : 0000000000000068
[10027.851748] Call trace:
[10027.854264]  mutex_is_locked+0x14/0x2c
[10027.858121]  msm_gem_shrinker_count+0x70/0xec
[10027.862603]  shrink_slab+0xc0/0x4b4
[10027.866187]  shrink_node+0x4a8/0x818
[10027.869860]  kswapd+0x624/0x890
[10027.873097]  kthread+0x11c/0x12c
[10027.876424]  ret_from_fork+0x10/0x18
[10027.880102] Code: f9000bf3 910003fd aa0003f3 d503201f (f9400268)
[10027.886362] ---[ end trace df5849a1a3543251 ]---
[10027.891518] Kernel panic - not syncing: Fatal exception
Signed-off-by: default avatarAkhil P Oommen <akhilpo@codeaurora.org>
Signed-off-by: default avatarRob Clark <robdclark@chromium.org>
parent 3c128638
......@@ -996,10 +996,8 @@ int msm_gem_new_handle(struct drm_device *dev, struct drm_file *file,
static int msm_gem_new_impl(struct drm_device *dev,
uint32_t size, uint32_t flags,
struct drm_gem_object **obj,
bool struct_mutex_locked)
struct drm_gem_object **obj)
{
struct msm_drm_private *priv = dev->dev_private;
struct msm_gem_object *msm_obj;
switch (flags & MSM_BO_CACHE_MASK) {
......@@ -1025,15 +1023,6 @@ static int msm_gem_new_impl(struct drm_device *dev,
INIT_LIST_HEAD(&msm_obj->submit_entry);
INIT_LIST_HEAD(&msm_obj->vmas);
if (struct_mutex_locked) {
WARN_ON(!mutex_is_locked(&dev->struct_mutex));
list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
} else {
mutex_lock(&dev->struct_mutex);
list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
mutex_unlock(&dev->struct_mutex);
}
*obj = &msm_obj->base;
return 0;
......@@ -1043,6 +1032,7 @@ static struct drm_gem_object *_msm_gem_new(struct drm_device *dev,
uint32_t size, uint32_t flags, bool struct_mutex_locked)
{
struct msm_drm_private *priv = dev->dev_private;
struct msm_gem_object *msm_obj;
struct drm_gem_object *obj = NULL;
bool use_vram = false;
int ret;
......@@ -1063,14 +1053,15 @@ static struct drm_gem_object *_msm_gem_new(struct drm_device *dev,
if (size == 0)
return ERR_PTR(-EINVAL);
ret = msm_gem_new_impl(dev, size, flags, &obj, struct_mutex_locked);
ret = msm_gem_new_impl(dev, size, flags, &obj);
if (ret)
goto fail;
msm_obj = to_msm_bo(obj);
if (use_vram) {
struct msm_gem_vma *vma;
struct page **pages;
struct msm_gem_object *msm_obj = to_msm_bo(obj);
mutex_lock(&msm_obj->lock);
......@@ -1105,6 +1096,15 @@ static struct drm_gem_object *_msm_gem_new(struct drm_device *dev,
mapping_set_gfp_mask(obj->filp->f_mapping, GFP_HIGHUSER);
}
if (struct_mutex_locked) {
WARN_ON(!mutex_is_locked(&dev->struct_mutex));
list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
} else {
mutex_lock(&dev->struct_mutex);
list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
mutex_unlock(&dev->struct_mutex);
}
return obj;
fail:
......@@ -1127,6 +1127,7 @@ struct drm_gem_object *msm_gem_new(struct drm_device *dev,
struct drm_gem_object *msm_gem_import(struct drm_device *dev,
struct dma_buf *dmabuf, struct sg_table *sgt)
{
struct msm_drm_private *priv = dev->dev_private;
struct msm_gem_object *msm_obj;
struct drm_gem_object *obj;
uint32_t size;
......@@ -1140,7 +1141,7 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
size = PAGE_ALIGN(dmabuf->size);
ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj, false);
ret = msm_gem_new_impl(dev, size, MSM_BO_WC, &obj);
if (ret)
goto fail;
......@@ -1165,6 +1166,11 @@ struct drm_gem_object *msm_gem_import(struct drm_device *dev,
}
mutex_unlock(&msm_obj->lock);
mutex_lock(&dev->struct_mutex);
list_add_tail(&msm_obj->mm_list, &priv->inactive_list);
mutex_unlock(&dev->struct_mutex);
return obj;
fail:
......
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